early renal disease: when to call the nephrologist?
TRANSCRIPT
EARLY RENAL DISEASE: WHEN TO CALL THE NEPHROLOGIST?
McGill Refresher Course
Dr. Tiina Podymow
Associate Professor Nephrology
McGill University Health Centre
November 30, 2020
DISCLOSURES
• None
OBJECTIVES
1. How to identify patients who are at the greatest risk of end-stage renal failure and dialysis
2. Interpret urine protein
3. Knowthediagnosticfeaturesofnephrosclerosisvs.diabeticnephropathy
4. Management principles – what to expect
CASE
• 69 year old Afro Caribbean woman, Cr 146 µmol/L eGFR 35 ml/min
• Hypertension, DM2, longstanding pancytopenia
• Meds: ASA, candesartan, HCTZ, metformin
• O/E weight 76 kg, 135/84 mm Hg, HR 70’s, no edema
Cr relatively stable over years
GLOMERULOSCLEROSIS VS. GLOMERULONEPHRITIS
Normal glomerulus Glomerulosclerosis
<1 g/day protein
3g/day u proteinGN e.g. Kimmelstiel Wilson lesionsDiabetic nephropathy(only 10-20% of diabetics)
URINE PROTEIN
• To diagnose renal disease, you need to know if there is protein in the urine or not
• Hint: Order both, can interpret them separately
• Urine albumin/Cr ratio (ACR) mg/mmol
• Urine protein/Cr ratio g/g
URINE PROTEIN INTERPRETATION
• Urine albumin/Cr ratio: answers the question: is the endothelium healthy?
< 3 mg/mmol: yes >3 mg/mmol: no it might not be
• Urine protein/Cr in g/g is a surrogate for 24 hour urine collection and answers the question: is this a GN?
Higher microalbumin levelMagnifies risk of renal function decline
Higher microalbumin levelIndicates greater cardiovascular mortalityA marker of endothelial health
69F CR 146 MOL/L
Dipstick: trace protein, no hematuria
Urine microalbumin is positive- but not at the higher risk level of >30 mg/mmol. Urine total protein/Cr: This patient has CKD not due to diabetes
µ
DOES THIS PATIENT WITH CR 146 AND URINE P/CR 0.23 G/G HAVE DIABETIC NEPHROPATHY? NO
Clinically DM nephropathy: 1. Microalbuminuria2. Albuminuria3. nephrotic proteinuria = 3/g/4. THEN Cr5. Progression to ESRD
Kimmelstiel Wilson lesions
• 69 year old woman
• Cr 146 eGFR 36 ml/min
• Urine microalbumin 10.8 mg/mmol
• U protein/Cr ratio 0.23 g/g
• = Glomerulosclerosis
• U protein ≤ 1 g/day
• Relatively stable Cr
PATIENT DIAGNOSIS
• http://mdrd.com/ to calculate eGFR, KFRE http://kidneyfailurerisk.com/
WHAT TO EXPECT WITH GLOMERULOSCLEROSIS
• CKD associated with ≤ 1 g/d proteinuria and a slow decline in renal function
• Prognosis is actually quite good- e.g. at 5 years this patient only has a 5 % chance of needing dialysis
• Target BP ≤ 140/90 mm Hg
• Patients tend to be very “volume sensitive” - Cr fluctuates if they are volume contracted (hold sick day medications e.gdiuretics)
• No NSAIDS – can cause AKI. Favor e.g. gout to be treated with short course prednisone rather than NSAID
• Dose meds to GFR 36 ml/min (use mdrd.com and Uptodate to easily calculate)
USES OF KFRE IN CANADA
• <3 % at 5 years (in the absence of uACR >100, hematuria or pregnancy) • “Low risk letter”
• Management “secrets” of low-risk glomerulosclerosis patients: • yearly urine albumin/Cr to recalculate KFRE• BP targets <140/90 mm Hg• no NSAIDs, • dose medications to eGFR
• Clinic funding in Ontario and Alberta: need KFRE of 20% at 2 years or eGFR <15 to enter multidiscplinary pre-dialysis clinic
• >40% at 2 years need to plan for dialysis: PD education or vascular access creation
BLOOD PRESSURE
• Uncontrolled hypertension tends to accelerate all forms of renal disease
• Target: ≤ 130/80 mm Hg in CKD with ≥ 1 g/day proteinuria = uP/Cr of >1 g/g
• Glomerulosclerosis: ≤ 1 g/day proteinuria target ≤ 140/90 mm Hg.
• Note that for glomerulosclerosis ACEI or ARBS are not mandatory as they are in diabetic/proteinuric renal disease. If they are tolerated (e.g K is normal, no jump in Cr <15%), use them. If they are not tolerated CaCh blocker, beta blockers, alpha blockers, thiazide etc. to get the BP to target
NEW PATIENT 67F NO HISTORY OF DIABETES
27 10 12.3 11.3
Spot urine protein/Cr ratio is a surrogate for 24 hour collection. Units: g/g
28
67F GN- PLEASE CALL NEPHRO
10 5.9
CO FOLLOW WITH NEPHROLOGY
• CKD with kidney failure risk score calculated ≥3% at 5 years
• More than the equivalent of 1 g/day proteinuria or 100 mg/mmol albuminuria and any Cr
• Proteinuria with hematuria- need to rule out glomerulonephritis
• Pregnancy or contemplating pregnancy with any degree of renal impairment or proteinuria (because of the high risk of renal deterioration and preeclampsia)
A WORD ABOUT SGLT-2 INHIBITORS
CREDENCEDAPA-CKDEMPA-KIDNEY
SLGT-2 Inhibitors:PRESERVED RENAL FUNCTION in trials
DECISION ALGORITHM FOR SGLT2-I
Li et al. CJASN. 2020; 15: 1678–1688
< 3 mg/mmol < 3-30 mg/mmol > 30 mg/mmol
SUMMARY
• When to call the nephrologist?
• In CKD, use urine albumin/Cr ratio (ACR) and KFRE to risk stratify, >5-10% consider referral
• If nephrotic proteinuria (total protein/Cr ratio > 3 g/g) always refer
• If low risk, annual or semi-annual serum Cr, eGFR, urine ACR and monitor targeted blood pressure, avoid NSAIDs. The lower the GFR, the more they could cause AKI.
• Presence of albuminuria and proteinuria: powerful markers for the tempo of renal disease and >30 mg/mmol always accelerate it
• Hypertension accelerates the loss of kidney function. Urine protein quantification helps establish BP treatment targets (<130 vs. 140/90 mm Hg per Canadian Hypertension Guidelines)